土壤液化所引致的土壤剪力強度損失，為地震災害中眾多大地結構物損壞的主因之一。本研究以中大地工離心機振動台，搭配積層式剪力試驗箱進行一維自由場土壤之離心振動台模型試驗，將30cm高的均質砂土模型試體置於80g重力場情況下，模擬24m厚之乾燥或飽和砂土層的受振反應。於試體基盤處輸入不同振幅大小之1Hz正弦波其延時為16秒，模擬乾燥砂土層受振以及飽和砂土層受振且淺層土壤發生液化的現象，同時利用加速度計陣列與孔隙水壓計陣列，量測不同位置深度的受振反應。 利用加速度計歷時以及孔隙水壓計歷時資料，可計算得到不同深度土層的剪應變、剪應力並進而求得剪力模數。研究中發現，在乾砂試體內有明顯剪力波向上傳遞的現象，並有地盤放大效應的產生。於飽和砂試體內，藉由所量測到的感測計歷時資料變化趨勢可以發現土壤膨脹以及突波情況的發生。 The relationship of shear stress and shear strain of sandy soil is an important parameter and need to determination when soil stiffness and strength degraded as a result of sand liquefaction. Centrifuge modeling tests can provide an alternative source of information and reliable test results for assessing soil mechanism under shaking situation. The centrifuge model was conducted to simulate the seismic response for a 24m thick sandy soil deposit under an artificial gravity field of 80g. The testing models are subjected to different magnitude base-input acceleration of 1Hz and 16 seconds duration. A series of accelerometer and pore water pressure transducer arrays were installed to record the soil seismic response. Utilizing the acceleration history and the pore pressure history, the shear stress and shear strain at different depths can be obtained. And then the shear modulus can be acquired through calculation. From this research, the phenomenon of shear wave propagating upward is obviously being seen in dry sand, so is the site effect. The soil dilatation and surge can be found in saturated sand.
